Age-associated changes in decorin in rat mandibular condylar cartilage

The sm:lll proteoglycan decorin strongly binds the fibrils of collagen type s I and II; this interaction is thought to play a part in the maintenance o l: tissue integrity and biomechanical properties. In limb articular cartila ge, there is evidence that decorin synthesis increases with age and that it is elevated in response to increased loading or in osteoarthritic cartilag e. The aim here was to characterize the presence and relative amount of dec orin in the condylar cartilage of the temporomandibular joint (TMJ) with ma turation by Western blotting, and to assess its tissue localization by immu nohistochemistry. Comparative data were obtained from tibial articular cart ilage, which has been extensively studied. Cartilage from the mandibular co ndyle and tibial plateau was harvested from 24-day-old (growing) and 161-da y-old (young adult) female Sprague-Dawley rats. In growing animals, decorin appeared slightly more abundant in the mandibular condylar cartilage than in articular cartilage, whereas in young adult animals the decorin content in thf TMJ cartilage was noticeably less than in limb articular cartilage. Although there was an increase in decorin abundance with age at the TMJ, th e increase in decorin with age in limb articular cartilage was considerably more pronounced. These data indicate that, although decorin is present in mandibular condylar cartilage, its abundance: in adults is less than in lim b articular cartilage; thus, maturation-associated changes may be dissimila r in magnitude from those documented for limb articular cartilage, (C) 2000 Elsevier Science Ltd. All rights reserved.